-rich products, such as beetroot juice ( Hoon et al., 2013 ; Jones, 2014 ; McMahon et al., 2017 ). Dietary nitrate supplementation is a popular ergogenic aid among athletes of all abilities ( Garthe & Maughan, 2018 ; Maughan et al., 2018 ). While a growing body of research has investigated the effects of
Philip Hurst, Samantha Saunders, and Damian Coleman
Kristin L. Jonvik, Jan-Willem van Dijk, Joan M.G. Senden, Luc J.C. van Loon, and Lex B. Verdijk
± SD . BMI = body mass index. Study Design In a double-blinded, randomized, crossover design, subjects underwent two 6-day supplementation periods (1 and 2), with either 140 ml/day of nitrate-rich (BR; ∼800 mg/day nitrate) or nitrate-depleted (PLA [placebo]) beetroot juice (Beet It; James White Drinks
Ozcan Esen, Ceri Nicholas, Mike Morris, and Stephen J. Bailey
consume either nitrate-rich beetroot juice (BRJ) or nitrate-depleted beetroot juice (PLA) for 3 days, in a randomized, double-blind, crossover design. A minimum washout period of 72 hours separated the BRJ and PLA supplementation periods to ensure plasma NO 2 − concentration had returned to baseline. 4
Pablo Jodra, Raúl Domínguez, Antonio J. Sánchez-Oliver, Pablo Veiga-Herreros, and Stephen J. Bailey
NO 3 − supplementation, which is typically administered in the form of NO 3 − -rich beetroot juice (BJ), are attributed to its stepwise reduction to nitrite and, subsequently, nitric oxide (NO) as NO 3 − is considered biologically inert. 2 After NO 3 − supplementation, the increase in plasma
Matthew J. Barlow, Antonis Elia, Oliver M. Shannon, Angeliki Zacharogianni, and Angelica Lodin-Sundstrom
juice supplementation. Maximal apnea duration was also extended by 11%. Patrician and Schagatay ( 2016 ) also recently reported elevated postexercise SpO 2 values following submaximal horizontal underwater dives in a swimming pool subsequent to NO 3 − -rich (∼5 mmol) beetroot juice supplementation. In
Naomi M. Cermak, Peter Res, Rudi Stinkens, Jon O. Lundberg, Martin J. Gibala, and Luc J.C. van Loon
Dietary nitrate supplementation has received much attention in the literature due to its proposed ergogenic properties. Recently, the ingestion of a single bolus of nitrate-rich beetroot juice (500 ml, ~6.2 mmol NO3 −) was reported to improve subsequent time-trial performance. However, this large volume of ingested beetroot juice does not represent a realistic dietary strategy for athletes to follow in a practical, performancebased setting. Therefore, we investigated the impact of ingesting a single bolus of concentrated nitrate-rich beetroot juice (140 ml, ~8.7 mmol NO3 −) on subsequent 1-hr time-trial performance in well-trained cyclists.
Using a double-blind, repeated-measures crossover design (1-wk washout period), 20 trained male cyclists (26 ± 1 yr, VO2peak 60 ± 1 ml · kg−1 · min−1, Wmax 398 ± 7.7 W) ingested 140 ml of concentrated beetroot juice (8.7 mmol NO3 −; BEET) or a placebo (nitrate-depleted beetroot juice; PLAC) with breakfast 2.5 hr before an ~1-hr cycling time trial (1,073 ± 21 kJ). Resting blood samples were collected every 30 min after BEET or PLAC ingestion and immediately after the time trial.
Plasma nitrite concentration was higher in BEET than PLAC before the onset of the time trial (532 ± 32 vs. 271 ± 13 nM, respectively; p < .001), but subsequent time-trial performance (65.5 ± 1.1 vs. 65 ± 1.1 s), power output (275 ± 7 vs. 278 ± 7 W), and heart rate (170 ± 2 vs. 170 ± 2 beats/min) did not differ between BEET and PLAC treatments (all p > .05).
Ingestion of a single bolus of concentrated (140 ml) beetroot juice (8.7 mmol NO3 −) does not improve subsequent 1-hr time-trial performance in well-trained cyclists.
Matthew W. Hoon, Andrew M. Jones, Nathan A. Johnson, Jamie R. Blackwell, Elizabeth M. Broad, Bronwen Lundy, Anthony J. Rice, and Louise M. Burke
Beetroot juice is a naturally rich source of inorganic nitrate (NO3 −), a compound hypothesized to enhance endurance performance by improving exercise efficiency.
To investigate the effect of different doses of beetroot juice on 2000-m ergometer-rowing performance in highly trained athletes.
Ten highly trained male rowers volunteered to participate in a placebo-controlled, double-blinded crossover study. Two hours before undertaking a 2000-m rowing-ergometer test, subjects consumed beetroot juice containing 0 mmol (placebo), 4.2 mmol (SINGLE), or 8.4 mmol (DOUBLE) NO3 −. Blood samples were taken before supplement ingestion and immediately before the rowing test for analysis of plasma [NO3 −] and [nitrite (NO2 −)].
The SINGLE dose demonstrated a trivial effect on time to complete 2000 m compared with placebo (mean difference: 0.2 ± 2.5 s). A possibly beneficial effect was found with DOUBLE compared with SINGLE (mean difference –1.8 ± 2.1 s) and with placebo (–1.6 ± 1.6 s). Plasma [NO2 −] and [NO3 −] demonstrated a dose-response effect, with greater amounts of ingested nitrate leading to substantially higher concentrations (DOUBLE > SINGLE > placebo). There was a moderate but insignificant correlation (r = –.593, P = .055) between change in plasma [NO2 −] and performance time.
Compared with nitratedepleted beetroot juice, a high (8.4 mmol NO3 −) but not moderate (4.2 mmol NO3 −) dose of NO3 − in beetroot juice, consumed 2 h before exercise, may improve 2000-m rowing performance in highly trained athletes.
David J. Muggeridge, Christopher C. F. Howe, Owen Spendiff, Charles Pedlar, Philip E. James, and Chris Easton
The aim of the current study was to determine the effects of dietary nitrate ingestion on parameters of submaximal and supramaximal exercise and time trial (TT) performance in trained kayakers. Eight male kayakers completed four exercise trials consisting of an initial discontinuous graded exercise test to exhaustion and three performance trials using a kayak ergometer. The performance trials were composed of 15 min of paddling at 60% of maximum work rate, five 10-s all-out sprints, and a 1 km TT. The second and third trials were preceded by ingestion of either 70 ml nitrate-rich concentrated beetroot juice (BR) or tomato juice (placebo [PLA]) 3 hr before exercise using a randomized crossover design. Plasma nitrate (PLA: 33.8 ± 1.9 μM, BR: 152 ± 3.5 μM) and nitrite (PLA: 519.8 ± 25.8, BR: 687.9 ± 20 nM) were higher following ingestion of BR compared with PLA (both p < .001). VO2 during steady-state exercise was lower in the BR trial than in the PLA trial (p = .010). There was no difference in either peak power in the sprints (p = .590) or TT performance between conditions (PLA: 277 ± 5 s, BR: 276 ± 5 s, p = .539). Despite a reduction in VO2, BR ingestion appears to have no effect on repeated supramaximal sprint or 1 km TT kayaking performance. A smaller elevation in plasma nitrite following a single dose of nitrate and the individual variability in this response may partly account for these findings.
Kristin E. MacLeod, Sean F. Nugent, Susan I. Barr, Michael S. Koehle, Benjamin C. Sporer, and Martin J. MacInnis
Beetroot juice (BR) has been shown to lower the oxygen cost of exercise in normoxia and may have similar effects in hypoxia. We investigated the effect of BR on steady-state exercise economy and 10-km time trial (TT) performance in normoxia and moderate hypoxia (simulated altitude: ~2500 m). Eleven trained male cyclists (VO2peak ≥ 60 ml·kg-1·min-1) completed four exercise trials. Two hours before exercise, subjects consumed 70 mL BR (~6 mmol nitrate) or placebo (nitrate-depleted BR) in a randomized, double-blind manner. Subjects then completed a 15-min self-selected cycling warm-up, a 15-min steady-state exercise bout at 50% maximum power output, and a 10-km time trial (TT) in either normoxia or hypoxia. Environmental conditions were randomized and single-blind. BR supplementation increased plasma nitrate concentration and fraction of exhaled nitric oxide relative to PL (p < .05 for both comparisons). Economy at 50% power output was similar in hypoxic and normoxic conditions (p > .05), but mean power output was greater in the normoxic TT relative to the hypoxic TT (p < .05). BR did not affect economy, steady-state SpO2, mean power output, or 10-km TT completion time relative to placebo in either normoxia or hypoxia (p > .05 in all comparisons). In conclusion, BR did not lower the oxygen cost of steady-state exercise or improve exercise performance in normoxia or hypoxia in a small sample of well-trained male cyclists.
George P. Robinson, Sophie C. Killer, Zdravko Stoyanov, Harri Stephens, Luke Read, Lewis J. James, and Stephen J. Bailey
Dietary supplementation with inorganic nitrate (NO 3 − ), typically in the form of NO 3 − -rich beetroot juice (BR), has emerged as a nutritional intervention to enhance exercise performance ( Jones et al., 2018 ). The ergogenic effects of dietary NO 3 − supplementation are attributed to the